Separate Study Decks and Homework in the library; drop the /create mode switch

Library ("Your icebox")
- Two tabs, never mixed: Study Decks (the folder + card library) and Homework
  (saved solutions and step-by-step guides). The active tab lives in the URL
  (/?tab=homework), so the sections are linkable and survive a reload.
- Decks tab keeps Import, the folder bar, stats and its own empty state — now
  a single decks-only CTA.
- Homework tab lists saved results as cards (mode icon, date, step count,
  preview) with Open and delete-with-confirm; its empty state has its own CTA
  ("Homework Solver") that opens the solver directly. Opening a card
  deep-links to /homework?open=<id>, which the screen opens on arrival.
- .segmented now also styles link segments (same control as settings).

/create
- The redundant "Study Deck | Homework Solver" toggle is gone: /create is the
  deck uploader only, and the bottom bar's + goes straight to it. Homework has
  its own screen, reached from the library tab, the drawer and CTAs.

Copy
- New keys (en + cs): tabDecks, tabHomework, homeworkHeroTitle, plus homework
  empty-state/open/step-count strings. The homework hero is now "Solve your
  homework" / "Vyřeš svůj úkol" — no study-deck text in the homework flow.
- Removed the now-unused ModeSwitch component and homework.title key.

Service worker: freezmo-v10.

Verified: library-tabs suite 37/37 (tab switching, context empty states,
deep-link opening, deletion, no switch on /create, heroes, redirects, desktop
grid, 360px + 44px targets, axe contrast en+cs light+dark), mobile 49/49,
i18n 27/27, desktop regression 74/74. Lint + build clean.

components/homework/HomeworkScreen.tsx

@@ -1,11 +1,12 @@
 "use client";
 
-import { useCallback, useMemo, useRef, useState, useSyncExternalStore } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState, useSyncExternalStore } from "react";
 
 import { documentsToText } from "@/lib/documents";
 import { ApiError, generateHomework, type HomeworkProgress } from "@/lib/client-api";
 import {
   deleteHomework,
+  getHomework,
   homeworkStore,
   saveHomework,
   sortHomework,
@@ -28,7 +29,7 @@ const MAX_TEXT_TO_SEND = 100_000;
 type View = { kind: "start" } | { kind: "loading" } | { kind: "record"; record: HomeworkRecord };
 
 /** The /homework screen: give it an assignment, pick a mode, get a result. */
-export function HomeworkScreen() {
+export function HomeworkScreen({ initialRecordId }: { initialRecordId?: string }) {
   const { t } = useI18n();
   const records = useSyncExternalStore(
     homeworkStore.subscribe,
@@ -49,6 +50,13 @@ export function HomeworkScreen() {
   const [againLoading, setAgainLoading] = useState(false);
   const abortRef = useRef<AbortController | null>(null);
 
+  // Deep link from the library's Homework tab: open the saved result directly.
+  useEffect(() => {
+    if (!initialRecordId) return;
+    const record = getHomework(initialRecordId);
+    if (record) setView({ kind: "record", record });
+  }, [initialRecordId]);
+
   /** Everything the API needs, built from the current input. */
   const buildPayload = () => {
     const readyDocuments = intake.documents.filter((entry) => entry.status === "ready" && entry.extracted);